Checking with FSUtility in Windows 7 i see their cluster size are both 4kb.
Checking the physical sector size the WD20EARS-00MVWB0﻿ has 512 but the WD20EARS-60MVWB0﻿ has 4096 instead.
What is the difference?

What's this model? Never seen it before. Mine ends at GC in the end of the modelnumber this ends with hp (SSDSA2M080G2HP). Which stands for Hawlett Packard right?
http://cgi.ebay.com/Intel-x25-80GB-2-5-SSD-Used-/220774195194